JP2995081B2 - Gas oil deep desulfurization method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a deep desulfurization method for remarkably reducing the sulfur concentration in a gas oil fraction.

[Prior art] Desulfurization of a gas oil fraction is industrially performed on an alumina carrier.
Using a catalyst supported in combination with cobalt, nickel, molybdenum or tungsten, at a temperature of 330-400 ° C, 30-
It is carried out exclusively under the conditions of a hydrogen pressure of 60 kg / cm ² · G and a liquid hourly space velocity of ^{2 to 10} hr ⁻¹ , and reduces the sulfur content in the gas oil fraction to about 0.1% by weight.

However, recently, from the viewpoint of environmental protection, it has been required to greatly reduce the sulfur content in diesel gas oil.

By the way, as a means for further reducing the sulfur content in the gas oil, there is a method of making the reaction conditions severe in the above-mentioned conventional desulfurization method.However, if the reaction temperature and the like are made severe without increasing the hydrogen pressure, the desulfurized gas oil is reduced. Coloring, especially fluorescent color,
Further, there is a problem that the catalyst life is shortened due to deposition of carbon.

[Problems to be Solved by the Invention] An object of the present invention is to solve the above problems, and an object of the present invention is to provide a method for deep desulfurizing a gas oil fraction under current mild conditions. It is in.

[Means for Solving the Problems] In the method for deep-desulfurizing gas oil of the present invention, the gas oil fraction is subjected to 30 to 60 kg in the presence of a catalyst previously supporting nickel and molybdenum (hereinafter referred to as “Ni-Mo catalyst”). / cm ² · G hydrogen pressure,
Hydrodesulfurization at a temperature of 280 to 400 ° C, followed by a catalyst supporting cobalt and molybdenum (hereinafter referred to as “Co-Mo catalyst”)
Is a desulfurization method in which hydrogen desulfurization is performed at a hydrogen pressure of 30 to 60 kg / cm ² · G and a temperature of 280 to 400 ° C. in the presence of sulfur.
Hydrodesulfurization is carried out at a hydrogen pressure and a temperature at which the following gas oil fraction is obtained.

The gas oil fraction referred to in the present invention refers to a fraction having a boiling range suitable for blending light oil having a quality suitable as a fuel for an internal combustion engine such as a diesel engine. The present invention can be applied to coal liquefied oil and the like.

The present invention relates to a gas oil fraction with Ni-Mo catalyst first, and then with Co
-Hydrogen desulfurization using a -Mo catalyst in two stages, as shown in a comparative example described later, a catalyst in which nickel, cobalt and molybdenum are simultaneously supported on a carrier (hereinafter referred to as "Ni-Co-Mo
A similar effect cannot be obtained by using a catalyst.

The Ni-Mo catalyst is, for example, alumina, silica, alumina-silica, alumina-boria, silica-alumina-
Magnesia, silica - alumina - nickel and molybdenum on a porous inorganic support with a refractory, such as titania, 0.5 to 10% by weight NiO, is suitably used those 5 to 30 wt% carried as MoO _3, particularly It is preferable that 1 to 6% by weight of NiO and 10 to 20% by weight of MoO ₃ are supported on an alumina carrier.

Further, on the same inorganic support and Co-Mo catalysts Ni-Mo catalyst, cobalt and molybdenum, 0.5 to 10 wt% as CoO, is preferably those carrying 5-30% by weight MoO _3, particularly 1-7% by weight as CoO on alumina carrier, M
those 10 to 20 wt% on a oO ₃ are preferred.

The Ni-Mo catalyst and the Co-Mo catalyst may be filled in one reaction vessel as upper and lower layers, or may be filled in separate reaction vessels and reacted by a method of connecting both vessels. It is preferable that the Ni-Mo catalyst and the Co-Mo catalyst are each filled into the reaction vessel by the same amount, but 20/80 to 80/20
(Ni-Mo catalyst / Co-Mo catalyst, volume ratio), the object of the present invention can be achieved.

The desulfurization conditions of the present invention do not need to be particularly severe conditions, and are usually the desulfurization conditions used for gas oil fractions or milder conditions, that is, a temperature of 280 to 400 ° C and a temperature of 30 to 60 kg /. It can be carried out under conditions such as a hydrogen pressure of cm ² · G, a liquid hourly space velocity of ¹ to 15 hr ⁻¹ , and a hydrogen-oil ratio of 50 to 1000 L / L. The desulfurization conditions were the same as for the reaction with the Ni-Mo catalyst.
It may be the same as that of the Co-Mo catalyst, but the optimum reaction conditions differ depending on the type of the catalyst. Generally, a Co-Mo catalyst is
It is better to carry out at a higher temperature than the Ni-Mo catalyst.

Further, in the present invention, a gas-liquid separator is provided between the preceding catalyst and the subsequent catalyst to separate hydrogen used for the reaction, and then fresh hydrogen is added, and the desulfurization reaction is performed with the subsequent catalyst. , The desulfurization effect can be further improved.

[Action] It is presumed that the deep desulfurization action of the present invention occurs because the type of sulfur to be desulfurized is different due to the difference in catalytic function between the Ni-Mo catalyst and the Co-Mo catalyst. That is, the Co-Mo catalyst is
Since the carbon-sulfur bond has a strong cleaving action and there is no steric hindrance, the sulfur-carbon bond easily desulfurizes a molecule (easy desulfurization compound) that comes into direct contact with the catalyst.
Molecules whose sulfur bonds cannot contact the catalyst (refractory compounds)
Is not expected to be desulfurized by this catalyst. However, if the reaction is performed at a high temperature, it is considered that steric hindrance is alleviated due to severe molecular motion, and desulfurization proceeds. On the other hand, Ni-Mo
It is presumed that the catalyst has a high hydrogenation ability and has a strong carbon-carbon cleavage effect, so that the structure of the compound, which is difficult to desulfurize due to steric hindrance, is changed, the sulfur-carbon bond can be brought into contact with the catalyst, and then desulfurization occurs Is done. Therefore, if hydrogenation is carried out with a Ni-Mo catalyst and then contact with a Co-Mo catalyst, the steric hindrance is alleviated and the desulfurization reaction is considered to proceed easily. In addition, Ni-Mo catalysts have high hydrogenation ability, so Co-
It is presumed that even when hydrodesulfurization is performed at a high temperature using a Mo catalyst, the generated coloring substance can be removed by hydrogenation.

[Example] (Reference Example 1) 10 g of a gas oil fraction (density 0.84 g / cm ³ , sulfur content 0.70 wt%, initial distillation point 232 ° C, 50% distillation point 291 ° C, 90% distillation point 321 ° C) Pre-sulfurized Co-Mo catalyst (Cobalt on alumina support
4% by weight as CoO, 15% by weight of molybdenum as MoO ₃
The mixture was loaded into a 50 cc autoclave together with 1 g, and reacted at a reaction temperature of 320 ° C. and a reaction hydrogen pressure of 50 atm for 1 hour. After completion of the reaction, the treated oil obtained by separating the catalyst from the reaction product was treated with a pre-sulfurized Ni-Mo catalyst (3% by weight of nickel as NiO on an alumina carrier and MoO _{3 on} molybdenum).
Was loaded again into a 50 cc autoclave and reacted for 1 hour at a reaction temperature of 320 ° C. and a reaction hydrogen pressure of 50 atm. The sulfur content in the obtained treated oil was quantified using a combustion tube type sulfur content tester (Yoshida Kagaku Kikai, QS-A2). The results are shown in Table 1. The treated oil did not show any fluorescent color.

(Reference Example 2) The same operation as in Reference Example 1 was performed except that the reaction temperature of the first desulfurization reaction using the Co-Mo catalyst was set to 340 ° C. The results are shown in Table 1. Note that no fluorescent color was observed in the treated oil.

(Reference Example 3) The same operation as in Reference Example 1 was performed, except that the reaction temperature of the desulfurization reaction using the Ni-Mo catalyst was changed to 340 ° C in Reference Example 1. The results are shown in Table 1. Note that no fluorescent color was observed in the treated oil.

(Example) Except that the reaction order of the Co-Mo catalyst and the Ni-Mo catalyst in the method of Reference Example 1 was reversed, the same operation as in Reference Example 1 was performed. The results are shown in Table 1. Note that no fluorescent color was observed in the treated oil.

(Comparative Example 1) 10 g of the same gas oil fraction as in Reference Example 1 was placed in a 50 cc autoclave together with 1 g of the same presulfurized Co-Mo catalyst as in Reference Example 1, and reacted at a reaction temperature of 320 ° C and a reaction hydrogen pressure of 50 atm for 1 hour. I let it. The sulfur content of the obtained treated oil was measured in the same manner as in Reference Example 1. The results are shown in Table 1.

(Comparative Example 2) 10 g of the same gas oil fraction as in Reference Example 1 was placed in a 50 cc autoclave together with 1 g of the pre-sulfurized Ni-Mo catalyst as in Reference Example 1, and reacted at a reaction temperature of 320 ° C and a reaction hydrogen pressure of 50 atm for 1 hour. I let it. The sulfur content of the obtained treated oil was measured in the same manner as in Reference Example 1. The results are shown in Table 1.

(Comparative Example 3) The same operation as in Comparative Example 1 was performed except that the reaction time was changed to 2 hours. The results are shown in Table 1.

(Comparative Example 4) 10 g of the same gas oil fraction as in Reference Example 1 was placed in a 50 cc autoclave together with 1 g of the pre-sulfurized Co-Mo catalyst as in Reference Example 1, and reacted at a reaction temperature of 320 ° C and a reaction hydrogen pressure of 50 atm for 1 hour. I let it. After the completion of the reaction, the reaction mixture was cooled, and the hydrogen used for the reaction was replaced with fresh hydrogen.
The reaction was performed again at a reaction temperature of 320 ° C. and a reaction hydrogen pressure of 50 atm for 1 hour. The sulfur content of the obtained treated oil was measured in the same manner as in Reference Example 1. The results are shown in Table 1.

(Comparative Example 5) 10 g of the same gas oil fraction as in Reference Example 1 was placed in a 50 cc autoclave together with 1 g of the pre-sulfurized Co-Mo catalyst as in Reference Example 1, and reacted at a reaction temperature of 320 ° C and a reaction hydrogen pressure of 50 atm for 1 hour. I let it. After completion of the reaction, the treated oil obtained by separating the catalyst from the reaction product was again placed in a 50 cc autoclave together with 1 g of the same pre-sulfurized Co-Mo catalyst as the new catalyst, and the reaction temperature was 320 ° C and the reaction hydrogen pressure was The reaction was performed at 50 atm for 1 hour, and the sulfur content of the treated oil was measured. The results are shown in Table 1.

(Comparative Example 6) 10 g of the same gas oil fraction as in Reference Example 1 was placed in a 50 cc autoclave together with 1 g of the pre-sulfurized Ni-Mo catalyst as in Reference Example 1, and reacted at a reaction temperature of 320 ° C and a reaction hydrogen pressure of 50 atm for 1 hour. I let it. After completion of the reaction, the treated oil obtained by separating the catalyst from the reaction product was again placed in a 50 cc autoclave together with 1 g of the same pre-sulfurized Ni-Mo catalyst as the new catalyst, and the reaction temperature was 320 ° C and the reaction hydrogen pressure was The reaction was performed at 50 atm for 1 hour, and the sulfur content of the treated oil was measured. The results are shown in Table 1.

(Comparative Example 7) Ni-C obtained by presulfurizing 10 g of the same light oil fraction as in Reference Example 1.
An o-Mo catalyst (1% by weight of nickel as NiO, 3% of cobalt as CoO, and 17% by weight of molybdenum as MoO _{3 on an} alumina carrier) was placed in a 50 cc autoclave together with 1 g, and the reaction temperature was 320 ° C. The reaction was carried out at a pressure of 50 atm for 1 hour, and the sulfur content of the treated oil was measured. The results are shown in Table 1.

(Comparative Example 8) 10 g of the same gas oil fraction as in Reference Example 1 was placed in a 50 cc autoclave together with 1 g of the same pre-sulfurized Co-Mo catalyst as in Reference Example 1, and reacted at a reaction temperature of 350 ° C and a reaction hydrogen pressure of 50 atm for 2 hours. I let it. As a result, the treated oil was noticeably colored in a fluorescent color.

As is clear from these results, as compared to increasing the contact time or performing two-step desulfurization treatment with the same catalyst,
It can be seen that the method of performing the two-stage desulfurization treatment by changing the type of the catalyst can significantly reduce the sulfur content.

[Effects of the Invention] In the present invention, since the gas oil fraction is subjected to two-stage desulfurization using a different catalyst, it can be subjected to deep desulfurization under mild conditions, and is a high-quality gas oil with little coloring such as fluorescent color. This has a special effect that a fraction can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C10G 45 / 06,45 / 08 C10G 65/04

Claims (1)

(57) [Claims] 1. A gas oil fraction is subjected to hydrogen pressure of 30 to 60 kg / cm ² · G in the presence of a catalyst supporting nickel and molybdenum at a pressure of 280 to 4 kg / cm ² · G.
Hydrodesulfurization at a temperature of 00 ° C., and then hydrodesulfurization at a hydrogen pressure of 30 to 60 kg / cm ² G at a temperature of 280 to 400 ° C. in the presence of a catalyst supporting cobalt and molybdenum, A deep desulfurization method for gas oil, comprising performing hydrodesulfurization at a hydrogen pressure and temperature at which a gas oil fraction having a sulfur content of 0.05 wt% or less is obtained.